Question:

Current flowing through a wire decreases linearly from 10A to zero in 4s as shown in the graph. Find the total charge flowing through the wire in the given time interval.

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For any linear change in current from \( I_{\text{initial}} \) to \( I_{\text{final}} \), the total charge can also be calculated using average current:
\( Q = I_{\text{avg}} \times \Delta t = \frac{I_{\text{initial}} + I_{\text{final}}}{2} \times \Delta t \).
In this specific case, \( Q = \frac{10 + 0}{2} \times 4 = 5 \times 4 = 20 \text{ C} \).
Updated On: Apr 23, 2026
  • 40C
  • 20C
  • 10C
  • 80C
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The Correct Option is B

Solution and Explanation

Step 1: Understanding the Question:
The total charge flowing through a circuit component is equal to the area under its current-time (\( I-t \)) graph.
Step 2: Key Formula or Approach:
The charge \( Q \) is given by the definite integral of current over time:
\[ Q = \int I(t) dt \]
Geometrically, this corresponds to the area of the region between the graph and the time axis.
Step 3: Detailed Explanation:
The provided graph forms a right-angled triangle with the following dimensions:
- Base (\( \Delta t \)) = 4 s
- Height (initial current \( I_0 \)) = 10 A
The area of a triangle is calculated using the formula:
\[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} \]
Substituting the values:
\[ Q = \frac{1}{2} \times 4 \text{ s} \times 10 \text{ A} = 20 \text{ C} \]
Step 4: Final Answer:
The total charge flowing through the wire is 20C.
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